# C validating a credit card number

The algorithm to validate a credit card number starts by adding the value of every other digit, starting from the right-most digit and working left.

Next, you do the same thing with the digits skipped in the first step, but this time you double the value of each digit and add the value of each digit in the result.

The length is in between 13 to 19 characters and contains only numbers and no space in between.

Credit Card / Debit Card Number Checker tool is designed to check the validity of Credit Card / Debit Card Number and check the (BIN) base on updated database.

You should use these numbers only to test your validation strategies and for bogus data.

In the case of payment gateway integrations there is another drawback.

Kindly take note that, the database is accurate but not perfect.

The tool is provided for informational purposes only.

Note that the algorithm used here is freely available across the web even

The Luhn test is used by some credit card companies to distinguish valid credit card numbers from what could be a random selection of digits.

#define ORDER_PP_DEF_8luhn_wk ORDER_PP_FN( \8fn(8N, \ 8lets((8P, 8unzip(8N, 8nil, 8nil, 8true)) \ (8O, 8seq_fold(8plus, 0, 8tuple_at_0(8P))) \ (8E, 8seq_fold(8plus, 0, \ 8seq_map(8dig_map, 8tuple_at_1(8P)))), \ 8is_0(8remainder(8plus(8O, 8E), 10)))) )#define ORDER_PP_DEF_8unzip ORDER_PP_FN( \8fn(8S, 8L, 8R, 8O, \ 8if(8is_nil(8S), \ 8pair(8L, 8R), \ 8if(8O, \ 8unzip(8seq_tail(8S), 8seq_push_back(8seq_head(8S), 8L), \ 8R, 8false), \ 8unzip(8seq_tail(8S), 8L, \ 8seq_push_back(8seq_head(8S), 8R), 8true)))) ) #lang racket (define (luhn-test n) (let loop ([n n] [odd? a\Faild$ include "seed7_05.s7i"; const func boolean: luhn Test (in string: card Number) is func result var boolean: luhn Test is FALSE; local var integer: index is 0; var integer: digit is 0; var boolean: is Odd is TRUE; var integer: odd Sum is 0; var integer: even Sum is 0; begin for index range length(card Number) downto 1 do digit := integer parse str(card Number[index]); if is Odd then odd Sum := digit; else even Sum := digit div 5 (2 * digit) rem 10; end if; is Odd := not is Odd; end for; luhn Test := (odd Sum even Sum) rem 10 = 0; end func; const proc: main is func local var string: card Number is ""; begin for card Number range [] ("49927398716", "49927398717", "1234567812345678", "1234567812345670") do writeln(card Number ; j = j 1 sum = sum d :(ln2)ln3 luhn = 0; luhn = eq(remdr(sum,10),0) 1 :(return)luhn_end * # Test and display test = " output = luhn(n) ': ' n" n = '49927398716'; eval(test) n = '49927398717'; eval(test) n = '1234567812345678'; eval(test) n = '1234567812345670'; eval(test)end Works with SPARK GPL 2010 and GPS GPL 2010. 9 then digit Sum (n div 10 n mod 10) else n fun luhn_sum [] = 0 | luhn_sum [d] = d | luhn_sum (d::d'::ds) = d digit Sum (2*d') luhn_sum dsin fun luhn_test n = luhn_sum (rev Digits n) mod 10 = 0 val res = map luhn_test [49927398716, 49927398717, 1234567812345678, 1234567812345670];end; (*[opening file "luhn.sml"] CREATE FUNCTION dbo._Credit Card Num Check( @str CCNum Var Char(40) )RETURNS Var Char(7)ASBEGIN DECLARE @string Var Char(40) = REVERSE(@str CCNum); -- usage: set once, never changed DECLARE @str S2Values Var Char(10) = '0246813579'; -- constant: maps digits to their S2 summed values DECLARE @table TABLE (ID INT, Value INT, S_Value INT); -- ID=digit position. DECLARE @p INT = 0; -- loop counter: position in string -- Convert the reversed string's digits into rows in a table variable, S_Values to be updated afterwards WHILE @p /:") SET esum=SUM (estring) SET s2=APPEND (s2,esum) ELSE SET s2=APPEND (s2,even) ENDIF ELSE SET s1=APPEND(s1,oe) ENDIF ENDLOOPSET s1=SUM(s1),s2=SUM(s2)SET checksum=s1 s2SET c=CENTER(c,-adjust)IF ("0") THEN PRINT c,"true"ELSE PRINT c,"false"[email protected](do (defun luhn (num) (for ((i 1) (sum 0)) ((not (zerop num)) (zerop (mod sum 10))) ((inc i) (set num (trunc num 10))) (let ((dig (mod num 10))) (if (oddp i) (inc sum dig) (let ((dig2 (* 2 dig))) (inc sum ( (trunc dig2 10) (mod dig2 10)))))))))@(collect :vars nil)@@(output)@ccnumber - 9, n - 9, n)) Mod 10 = 0 End Function Sub Main() Console. Val ) next dim sum as integer for each digit as string in digit Arr sum = sum digit.

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